1. Field of the Invention
The present invention relates to an image data adjusting technique for adjusting image quality of image data.
2. Description of the Related Art
Quality of image data generated by a digital still cameras (DSC) or digital video cameras (DVC) can be adjusted in any desired manner using an image retouching application on a personal computer. Image retouching applications typically have an image adjusting function that automatically adjusts the quality of image data, and quality of image data output from an output device may be improved using this image adjusting function. Known image output devices include, for example, CRTs, LCDs, printers, projectors, and television receivers.
A printer driver for a printer also has a function for automatically adjusting image quality, and quality of printed images can be improved using such a printer driver as well.
Brightness is one important factor determining image quality of image data. If the brightness of image data has been set to the proper brightness level, the user will recognize the high image quality of the image. Image data brightness is strongly affected by the position of the light source when image data is generated. For example, image data is sometimes generated under condition in which the sun or other light source is situated behind a subject (backlighting). Under such backlit conditions, in some instances sufficient light will not fall on the side of an intended subject that is facing the camera, resulting in generation of image data in which the intended is darker than the proper brightness level. Thus, methods that analyze image data brightness and adjust the image data on the basis of the results so as to increase brightness in dark areas and improved image quality are used.
With the automatic image quality adjusting function provided by an image retouching application or printer driver, quality corrections are made on the basis of image data having standard quality characteristics. On the other hand, image data being subjected to image processing can be produced under various conditions. For example, the position of a subject within an image may be set arbitrarily according to user preference, and shooting location. In some instances image data is generated using a flash or other supplemental light source; and shooting takes place under different conditions depending on shooting location, for example, shooting outdoors, and shooting indoors.
For this reason, in some instances image quality of an image overall cannot be improved through quality corrections to an image containing dark areas, made on the basis of image data having standard quality characteristics. This problem is not limited to DSCs, and is a problem common to DVCs and other such image producing devices.